1. Field of the Invention
The present invention generally relates to a stacked package structure for reducing the package volume of an acoustic micro-sensor.
2. Description of the Prior Art
Packaging of an acoustic micro-sensor made by Micro-Electro-Mechanical Systems (MEMS) has been a key issue. Conventionally, wire bonding is used to connect an IC device and an acoustic micro-sensor.
In U.S. Pat. No. 6,781,231 “Microelectromechanical System Package with Environmental and Interference Shield” as shown in FIG. 1, surface mounted devices (SMD's) 12, 14, 16 such as an IC device and an acoustic micro-sensor are mounted on a substrate 18 and are connected by wire bonding. In FIG. 1, the package volume is very large because the IC device and the acoustic micro-sensor are connected by wire bonding.
In U.S. Pat. Appl. No. 2005/0185812 “Miniature Silicon Condenser Microphone and Method for Producing the Same” as shown in FIG. 2, an IC device 22 and an acoustic micro-sensor 24 are surface-mounted on a substrate 26. A recess as a back chamber 28 is formed on the substrate 26 corresponding to a position whereon the acoustic micro-sensor 24 is formed. Therefore, the noise generated due to the vibration of the sensing thin film of the acoustic micro-sensor is reduced. However, in this patent, the substrate is recessed because the IC device and the acoustic micro-sensor occupy the area on the substrate. Therefore, the package volume is large and the manufacturing is complicated.
In U.S. Pat. No. 6,178,249 “Attachment of a Micromechanical Microphone” as shown in FIG. 3, flip-chip technology is used to form an acoustic micro-sensor 32 on an IC device 34 and a back chamber 38 enveloped by an insulating ring 36 between the acoustic micro-sensor 32 and the IC device 34 so as to reduce noise generated due to the vibration of the sensing thin film of the acoustic micro-sensor. However, in this patent, a back chamber 38 is required. Therefore, the package volume is large.
Accordingly, there is need in providing a stacked package structure for reducing the package volume of an acoustic micro-sensor using flip-chip technology to stack an acoustic micro-sensor on an integrated circuit (IC) device having a recess as a back chamber and cover the acoustic micro-sensor using a glass substrate or a planar substrate with an aperture so as to reduce the package volume of the acoustic micro-sensor.